The TRUE scale of the world's biggest iceberg: Enormous 'megaberg' that broke free last month is just under one TRILLION tonnes - 100 million times as heavy as the Eiffel Tower, scientists say

New satellite measurements reveal the true scale of the world's largest iceberg. 

Called A23a, the platform of floating ice has a surface area of 1,500 square miles, a volume of 263 cubic miles and a mass just below one trillion tonnes.

That makes it not only four times as big as Greater London, but a whopping 100 million times as heavy as the Eiffel Tower in Paris. 

A23a – which is shaped like a 'tooth' – is now being carried northwards by wind and ocean currents 'at speed' after 30 years of being grounded to the ocean floor.

It's drifting past the Antarctic Peninsula (which sticks out from the mainland like a tail) and should break down due to rougher waters once it reaches the open ocean. 

According to the British Antarctic Survey (BAS), which visited A23a last week, the iceberg is travelling north at a rate of about 30 miles per day. 

There's a chance the huge berg could disrupt the feeding routines of wildlife such as penguins – for example, if it parked in an area where foraging usually happens. 

'It depends on its trajectory, but there is potential for impact to wildlife if it approaches any of the sub-Antarctic islands,' a BAS spokesperson told MailOnline.

A23a is the surviving largest fragment of an iceberg that broke free of the Antarctic's Filchner Ice Shelf in August 1986.

It had only moved a couple of hundred miles when it became stuck, or 'grounded' to the ocean floor – and ended up becoming stationary for the next 30 years. 

Icebergs 'ground' on the ocean floor when their keel (the bit below the water's surface) is deeper than the water's depth. 

The European Space Agency's CryoSat satellite has found that one part of the iceberg's base in particular stuck out a lot deeper, making it act like an anchor. 

Scientists revealed last month that the berg is on the move again, being carried northwards by wind and ocean currents. 

The European Space Agency's satellite imagery shows the iceberg approaching Clarence Island and Elephant Island, both near the tip of the Antarctic Peninsula. 

'A23a has put a spurt on and is heading quickly away from Antarctic waters,' the agency said on December 1.

'Like most icebergs from the Weddell sector, A23a is likely to end up in the South Atlantic on a path called iceberg alley.' 

Experts at BAS aboard Britain's polar research ship, the RRS Sir David Attenborough, snapped shots of A23a last week, after they they crossed its path during a 'lucky' encounter. 

The team took samples of ocean surface waters around the iceberg’s route to help determine what life could form around it and how the iceberg and others like it affect carbon in the ocean.

'It is amazing to see this huge berg in person – it stretches as far as the eye can see,' said Andrew Meijers, chief scientist aboard the research ship. 

American planetary scientist Lindy Elkins-Tanton, who was part of another voyage to visit A23a last month, has been posting snaps of the berg to X. 

In one post, she said it 'feels like sailing alongside a new country'. 

A23a is currently the largest iceberg in the world, but this title won't last forever because all icebergs eventually fragment. 

As it gets further north, water temperatures will see A23a get thinner before it breaks apart and melts completely. 

The former record holder was A76, which detached from an ice shelf in the Weddell Sea in May 2021, but it has since fragmented into three pieces.